1. Field of the Invention
This invention relates to short circuit suppression in charging and discharging of a lithium-ion secondary battery.
2. Description of the Related Art
In view of a problem of global warming and depletion of fuel, an electric vehicle (EV) has been developed by each auto manufacturer. As a power source of the EV power, a lithium-ion secondary battery with high energy density is required. In recent years, an active material containing Si has been expected in order to obtain the high energy density. It has been known that Si has large volume changes associated with charging and discharging.
In general, a lithium-ion secondary battery has an electrode group constituted of a positive electrode, a negative electrode, and a separator.
In JP-2012-104320-A, as an example of a negative electrode active material, Si and silicon oxide are mentioned, and a cross-sectional structure of a battery in which the dimension of the negative electrode is larger than that of the positive electrode is illustrated.
In JP-2009-295289-A, a cross-sectional structure of a battery in which the dimension of the negative electrode is larger than that of the positive electrode is illustrated.
This is because Li released from the positive electrode is received at the negative electrode, and in a case where the negative electrode is small, Li may be precipitated in current collector foil-exposed part of the negative electrode terminal part.